Somalia's militant group al-Shabab says it will not allow aid groups it has banned from operating in famine-stricken areas of the country.

Definition of Famine:

The word famine is a term that is not used lightly by humanitarian organizations. The United Nations describes a crisis as a famine only when the following conditions are met:

Malnutrition rates exceed 30 percent

More than two people per 10,000 people are dying each day

Severe lack of food access for large population

Current Famine:

Almost half of Somalia's population, 3.7 million people, are affected by the current crisis with malnutrition rates in southern Somalia the highest in the world, surpassing 50 per cent in some areas. The United Nations says it is likely that tens of thousands have already have died, the majority of those being children.

The drought that has led to the current famine in parts of Somalia has also affected people in Kenya and Ethiopia.

Previous Famines in the Horn of Africa:

Somalia 1991-1992

Ethiopia 1984-1985

Ethiopia 1974

The al-Qaida-linked group has called the United Nations declaration of a famine in two areas under its control "propaganda."

This week the U.N. declared a famine in southern Somalia's Bakool and Lower Shabelle regions and said nearly half of Somalia's population needs urgent aid. On Friday the World Health Organization said five more regions in southern Somalia are on the brink of famine.

Thursday, Al-Shabab spokesman Sheikh Ali Mohamoud Rage accused the U.N. of exaggerating the crisis for political reasons. He said al-Shabab will allow increased aid only from foreign agencies currently working in its strongholds, not from organizations it has banned. But he did not specify which organizations.

Death rate increasing

Meanwhile, the U.N. refugee agency said Friday the death rate of starving Somalis reaching refugees camps in Ethiopia and Kenya is climbing and the exodus of Somalis is continuing at a high rates.

Relief groups are searching to ways to deliver life-saving aid inside the country to save lives and prevent the mass exodus of Somalis to overcrowded camps in neighboring countries.

Relief groups say personnel must keep a low profile to avoid being targeted by the militants, whose members sometimes demand payments and seize deliveries.

Somali Militants Will Block Aid to Famine-Stricken Areas

The U.N. estimates that tens of thousands of Somalis have already died of malnutrition. It warns a rapid increase in aid is needed to prevent the widespread loss of life.

Overall, the Horn of Africa is experiencing the worst drought in six decades. The U.N. has said more than 11 million people are in need of food aid.